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Normally Closed Current Sensors

Written by Henry Smith | Mar 14, 2017 4:00:00 AM

Occasionally a customer will call our Technical Support to ask if we offer any Normally Closed current sensors. While it is true that all of our self-powered AC current sensors only offer a Normally Open Solid State contact, we do carry several relay & AC sensor combinations that can be configured to function as powered Normally Closed current sensors. Specifically, those models are the RIBXLCRA & RIBXLCRF, RIBXLCJA & RIBXLCJF, RIBXLSRA & RIBXLSRF, and RIBXLSJA & RIBXLSJF.

Each of the above models comes in a 4" by 4" plastic enclosure. Either a solid core or split core remote current sensor is also included. When wired as shown below, the device will function as a current sensor with a SPDT relay output.

How it Works:

When current through the load wire exceeds the threshold (see datasheet) of the device, the sensor feedback contact will close. This will allow the voltage connected to the upper screw terminal to reach the on-board relay coil. Once the relay coil is energized, the N/O relay contact will close and the N/C relay contact will open.

The diagram above most closely represents the RIBXLCRA & RIBXLCRF, but all other models would be wired similarly. The relay output of the RIBXLSRA & RIBXLSRF and RIBXLSJA & RIBXLSJF is slightly different, as it is only a SPST that is selectable between N/O and N/C, and those models also have an override switch built it.

If you have any questions, please feel free to call or email our Technical Support. We are always happy to help!

About Functional Devices, Inc.

Functional Devices, Inc., located in the United States of America, has been designing and manufacturing quality electronic devices since 1969. Our mission is to enhance lives in buildings and beyond. We do so by designing and manufacturing reliable, high-quality products for the building automation industry.  Our suite of product offerings include RIB relays, current sensors, power controls, power supplies, transformers, lighting controls, and more.

We test 100% of our products, which leads to less than 1 out of every 16,000 products experiencing a failure in the field.